Active robotic pin placement in total knee arthroplasty

ABSTRACT

A surgical device is provided includes a hand-held portion with a working portion movably coupled to the hand-held portion for driving a tool. Actuators are provided for moving the working portion with each of the actuators having a travel range. An indicator notices a user when at least one of actuators is: (i) within the travel range; (ii) approaching a travel limit of the travel range; or (iii) outside the travel range. A surgical system is also provided inclusive the surgical device and a computing system configured to activate the indicator.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claim is a continuation of U.S. application Ser. No.15/778,811, filed May 24, 2018; that in turn is a US National PhaseApplication of Serial Number PCT/US2016/062020, filed Nov. 15, 2016;U.S. Provisional Application Ser. No. 62/349,562, filed Jun. 13, 2016and U.S. Provisional Application Ser. No. 62/259,487, filed Nov. 24,2015; the contents of which are hereby incorporated by reference intheir entirety.

FIELD OF THE INVENTION

The present invention generally relates to computer assisted surgery,and more specifically, to systems and methods for actively aligning cutguides for total knee arthroplasty.

BACKGROUND

Total knee arthroplasty (TKA) is a surgical procedure in which thearticulating surfaces of the knee joint are replaced with prostheticcomponents, or implants. TKA requires the removal of worn or damagedarticular cartilage and bone on the distal femur and proximal tibia. Theremoved cartilage and bone is then replaced with synthetic implants,typically formed of metal or plastic, to create new joint surfaces.

The position and orientation (POSE) of the removed bone, referred to asbone cuts or resected bone, determines the final placement of theimplants within the joint. Generally, surgeons plan and create the bonecuts so the final placement of the implants restores the mechanical axisor kinematics of the patient's leg while preserving the balance of thesurrounding knee ligaments. Even small implant alignment deviationsoutside of clinically acceptable ranges correlates to less than optimaloutcomes and increased rates of revision surgery. In TKA, creating thebone cuts to correctly align the implants is especially difficultbecause the femur requires at least five planar bone cuts to receive atraditional femoral prosthesis. The planar cuts on the distal femur mustbe aligned in five degrees of freedom to ensure a proper orientation:anterior-posterior translation, proximal-distal translation,external-internal rotation, varus-valgus rotation, and flexion-extensionrotation. Any malalignment in any one of the planar cuts or orientationsmay have drastic consequences on the final result of the procedure andthe wear pattern of the implant.

Cutting guides, also referred to as cutting blocks or cutting jigs, arecommonly used to aid in creating the bone cuts. The cutting guidesinclude guide slots to restrict or align a bone removal device, such asan oscillating saw, in the correct bone resection plane. Cutting guidesare advantageous for several reasons. One such advantage is that theguide slots stabilize the bone removal device during cutting to ensurethe bone removal device does not deflect from the desired plane. Second,a single cutting guide may include multiple guide slots (referred toherein as an N-in-1 cutting block) which can define more than onecutting plane to be accurately resected, such as a 4-in-1 block, 5-in-1block . . . N-in-1 block. Thus, the surgeon can quickly resect two ormore planes once the cutting guide is accurately oriented on the bone.Still another advantage is that the guide slots and the working end ofthe oscillating saw are typically planar in shape and relatively thin,which make them ideal for creating planar bone cuts. The advantages ofusing a cutting guide are apparent, however, the cutting guide stillneeds to be accurately positioned on the bone prior to executing thecut. In fact, it is the placement of the guide slots on the bone thatremains one of the most difficult, tedious, and critical tasks forsurgeons during TKA.

Various techniques have been developed to help a surgeon correctly alignthe guide slots on the bone. Typical cutting guide systems include anumber of manual adjustment mechanisms that are used in conjunction withpassive navigation, image-guidance, or anatomical landmark referencing.Guide pins are used to temporarily fix the cutting guide in the generalorientation on the bone, and additional fine tuning adjustments are thenmade. One of the main drawbacks, however, is the complexity of thecutting guides. The manual adjustment mechanisms are usually quiteelaborate since the guide slots need to be oriented in six degrees offreedom. This requires extensive user training, which often predisposesa surgeon to use a particular implant or implant line that is specificfor a given cutting guide system even if another implant affords otheradvantages. Additionally, when orienting the cutting guides usinganatomical references, variations of the anatomy from patient to patientmay cause difficulty in accurately aligning the cutting guidesconsistently. Passive navigation and image-guidance may be useful, butthe surgeon has to constantly reference a monitor or other feedbackmechanism, introducing error and prolonging the operating procedure. Atypical total knee arthroplasty procedure may take approximately 60minutes to complete.

Other methods have also been developed to alleviate the use of cuttingguides. Haptic and semi-active robotic systems allow a surgeon to definevirtual cutting boundaries on the bone. The surgeon then manually guidesa cutting device while the robotic control mechanisms maintain thecutting device within the virtual boundaries. One disadvantage of therobotic system, however is the deflection of the cutting device that mayoccur when attempting to create a planar cut on the bone. The cuttingdevice may encounter curved surfaces on the bone causing the device toskip or otherwise deflect away from the resection plane. The resultingplanar cuts would then be misaligned, or at least difficult to createsince the cutting device cannot be oriented directly perpendicular tothe curved surface of the bone to create the desired bone cut. Cuttingguides, on the other hand, are removably fixed directly against thebone, and therefore deflection of the cutting device is greatlydecreased. In addition, the costs associated with haptic or semi-activerobotic systems are considerably higher than manual instrumentation.

Thus, there is a need for a system and method to take advantage of usinga cutting guide without the current time consuming and labor intensiveburden of orienting the cutting guide on the bone.

SUMMARY OF THE INVENTION

An alignment system for surgical bone cutting procedures includes aplurality of bone pins inserted within a virtual plane relative to a cutplane to be created on a subject's bone, a cutting guide configured tobe received onto said plurality of bone pins, and one or more guideslots within said cutting guide, said one or more guide slots configuredto guide a surgical saw to make surgical cuts on the subject's bone.

A method for aligning a cutting guide on a subject's bone includesdetermining one or more cut planes from a surgical plan obtained withplanning software. Determining one or more virtual planes relative toeach of the one or more cut planes to be created on the subject's bone.Aligning and inserting a plurality of bone pins within a virtual planefrom the one or more virtual planes. Attaching a cutting guideconfigured to clamp onto the plurality of inserted bone pins, andwherein one or more guide slots are within the attached cutting guide,the one or more guide slots configured to guide a surgical saw to makesurgical cuts on the subject's bone that correspond to the one or morecut planes.

A surgical device for pin insertion in a subject's bone to aid inperforming a bone cutting procedure includes a working portionconfigured to articulate a pin for insertion in the subject's bone. Ahand-held portion pivotably connected to the working portion by a frontlinear rail and rear linear rail, where the front linear rail and therear linear rail are actuated by a set of components in the hand-heldportion to adjust pitch and translation of the working portion relativeto the hand-held portion, the front linear rail and the rear linear raileach having a first end and a second end. A tracking array having a setof three or more fiducial markers rigidly attached the working portionto permit a tracking system to track a position and orientation (POSE)of the working portion. The POSE of the pins upon insertion in the bonebeing used to assemble and align a cutting guide thereon to facilitatethe creation of a desired cut plane.

BRIEF DESCRIPTION OF THE DRAWING

The present invention is further detailed with respect to the followingdrawings. These figures are not intended to limit the scope of thepresent invention but rather illustrate certain attribute thereofwherein;

FIG. 1 depicts a surgical system to perform a procedure on a bone;

FIGS. 2A and 2B depicts a surgical device used in the surgical system;

FIG. 3 illustrates a virtual plane defined relative to a planned cutplane on a three dimensional model of a bone in accordance withembodiments of the invention;

FIGS. 4A and 4B depicts a universal distal cutting guide for creating adistal cut on a bone in accordance with embodiments of the invention asa front view (FIG. 4A) and perspective view (FIG. 4B);

FIG. 4C depicts bone pins positioned in the context of a bone;

FIG. 4D depicts the universal distal cutting guide of FIGS. 4A and 4Bsecured to bone using the bone pins of FIG. 4C;

FIGS. 5A-5D depicts a 4-in-1 cutting block for creating multiple cutplanes on a bone in accordance with embodiments of the invention inperspective view (FIG. 5A), side view (FIG. 5B), bottom view (FIG. 5C),and top view (FIG. 5D);

FIGS. 6A and 6B depicts a planar alignment guide for aligning a N-in-1block on a bone in accordance with embodiments of the invention inperspective view (FIG. 6A), and top view (FIG. 6B);

FIGS. 7A and 7B depicts an offset alignment guide for aligning a N-in-1block on a bone in accordance with embodiments of the invention inperspective view (FIG. 7A), and top view (FIG. 7B);

FIGS. 8A-8D depicts a channel created on the distal surface of the femurin perspective view (FIG. 8A) and in side view (FIG. 8B) for receivingan alignment guide in accordance with embodiments of the invention withthe alignment guide depicted in the channel in perspective view (FIG.8C) and top view (FIG. 8D);

FIGS. 9A and 9B depicts a universal distal cutting guide with a N-in-1cutting block alignment guide in a top perspective view (FIG. 9A),bottom perspective view (FIG. 9B), and in accordance with embodiments ofthe invention;

FIG. 9C depicts bone pins positioned in the context of a bone;

FIG. 9D depicts the universal cutting guide with a N-in-1 cutting blockalignment guide of FIGS. 9A and 9B secured to bone using the bone pinsof FIG. 9C;

FIGS. 10A and 10B depict a slotted alignment guide for aligning a N-in-1cutting block in accordance with embodiments of the invention inperspective view (FIG. 10A), and top view (FIG. 10B);

FIG. 10C depicts bone pins positioned in the context of a bone;

FIG. 10D depicts the universal cutting guide with a N-in-1 cutting blockalignment guide of FIGS. 10A and 10B secured to bone using the bone pinsof FIG. 10C;

FIGS. 11A-11E depict a 5-degree-of-freedom chamfer cutting guide forcreating multiple planar bone cuts in accordance with embodiments of theinvention;

FIGS. 12A-12D illustrate the placement of pins to receive a5-degree-of-freedom chamfer cutting guide in accordance with embodimentsof the invention;

FIGS. 13A and 13B depicts a pin alignment guide for aligning a pin in aspecific location on a bone in accordance with embodiments of theinvention;

FIGS. 14A and 14B depicts a cutting guide with attachment holes spaced adistance apart in accordance with embodiments of the invention;

FIGS. 15A and 15B illustrates at least two perpendicular channelscreated on the bone to receive the pin alignment guide in accordancewith embodiments of the invention;

FIGS. 16A and 16B depicts a referencing clamp alignment guide forcreating pilot holes on the bone to align a N-in-1 cutting block inaccordance with embodiments of the invention;

FIGS. 16C and 16D illustrates the use of the referencing clamp alignmentguide in accordance with embodiments of the invention;

FIG. 16E illustrates a stepped diameter drill bit for use with thereference alignment guide in accordance with embodiments of theinvention;

FIGS. 17A and 17B depict a plane clamp alignment guide for creatingpilot holes on a distal cut surface to align a N-in-1 cutting block inaccordance with embodiments of the invention;

FIG. 17C illustrates the use of the plane alignment guide in accordancewith embodiments of the invention;

FIGS. 18A and 18B depict a cross-section of a articulating pin-driverdevice, where FIG. 18A depicts the device having a pin in a retractedstate, and FIG. 18B depicts the device having a pin in an extended statein accordance with embodiments of the invention;

FIG. 18C is an exploded view that illustrates the components of aworking portion of the pin-driver device in accordance with embodimentsof the invention;

FIGS. 19A and 19B depicts and illustrate a bone stability memberattached to the pin-driver device and the use thereof in accordance withembodiments of the invention;

FIGS. 20A and 20B depicts a partial enclosure enclosing the workingportion in accordance with embodiments of the invention; and

FIGS. 21A and 21B depicts a full enclosure enclosing the working portionin accordance with embodiments of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention has utility as a system and method to aid asurgeon in efficiently and precisely aligning a cutting guide on apatient's bone. The system and method are especially advantageous fortotal knee arthroplasty and revision knee arthroplasty, however, itshould be appreciated that other medical applications may exploit thesubject matter disclosed herein such as high tibial osteotomies, spinalreconstruction surgery, and other procedures requiring the preciseplacement of a cutting guide to aid a surgeon in creating bone cuts.

The following description of various embodiments of the invention is notintended to limit the invention to these specific embodiments, butrather to enable any person skilled in the art to make and use thisinvention through exemplary aspects thereof.

Embodiments of the present invention may be implemented with a surgicalsystem. Examples of surgical systems used in embodiments of theinvention illustratively include a 1-6 degree of freedom hand-heldsurgical system, a serial-chain manipulator system, a parallel roboticsystem, or a master-slave robotic system, as described in U.S. Pat. Nos.5,086,401; 7,206,626; 8,876,830; 8,961,536; and 10,492,870; and U.S.Pat. App. No. 2013/0060278. In a specific embodiment, the surgicalsystem is a serial-chain manipulator system as described in U.S. Pat.No. 6,033,415 assigned to the assignee of the present application andincorporated by reference herein in its entirety. The manipulator systemmay provide autonomous, semi-autonomous, or haptic control and anycombinations thereof. In a specific embodiment, a tool attached to themanipulator system may be manually maneuvered by a user while the systemprovides at least one of power, active or haptic control to the tool.

With reference to the figures, FIG. 1 illustrates a 2-degree-of-freedom(2-DOF) surgical system 100. The 2-DOF surgical system 100 is generallydescribed in PCT Pub. US2015/051713, assigned to the assignee of thepresent application and incorporated by reference herein in itsentirety. The 2-DOF surgical system 100 includes a computing system 102,an articulating surgical device 104, and a tracking system 106. Thesurgical system 100 is able to guide and assist a user in accuratelyplacing pins coincident with a virtual pin plane that is definedrelative to a subject's bone. The virtual plane is defined in a surgicalplan such that a cut guide when assembled to the inserted pins align oneor more guide slots with the bone cuts required to receive a prostheticimplant in a planned position and orientation.

Articulating Surgical Device

FIGS. 2A and 2B illustrate the articulating surgical device 104 of the2-DOF surgical system 100 in more detail. The surgical device 104includes a hand-held portion 202 and a working portion 204. Thehand-held portion 202 includes an outer casing 203 of ergonomic designto be held and manipulated by a user. The working portion 204 includes atool 206 having a tool axis 207. The tool 206 is readily attached to anddriven by a motor 205. The hand-held portion 202 and working portion 204are connected by a front linear rail 208 a and a back linear rail 208 bthat are actuated by components in the hand-held portion 202 to controlthe pitch and translation of the working portion 204 relative to thehand-held portion 202. A tracking array 212, having three or morefiducial markers, is rigidly attached to the working portion 204 topermit a tracking system 106 to track the POSE of the working portion204. The fiducial markers may be active markers such as light emittingdiodes (LEDs), or passive markers such as retroreflective spheres. Aninput/output port in some inventive embodiments provides power and/orcontrol signals to the device 104; or the device may receive power frombatteries and control signals via a wireless connection alleviating theneed for electrical wiring to be connected to the device 104. In aparticular embodiment, the device 104 may receive wireless controlsignals via visible light communication as described in Int'l Pat. App.WO 2016/081931 assigned to the assignee of the present application andincorporated by reference herein in its entirety. The device 104 mayfurther include one or more user input mechanisms such as a trigger 214or a button.

Within the outer casing of the hand-held portion 202 are a frontactuator 210 a that powers a front ball screw 216 a and a back actuator210 b that powers a back ball screw 216 b. The actuators (210 a, 210 b)may be servo-motors that bi-directionally rotate the ball screws (216 a,216 b). A first end of the linear rails (208 a, 208 b) are attached tothe working portion 204 via hinges (220 a, 220 b), where the hinges (220a, 220 b) allow the working portion 204 to pivot relative to the linearrails (208 a, 208 b). Ball nuts (218 a, 218 b) are attached at a secondend of the linear rails (208 a, 208 b). The ball nuts (218 a, 218 b) arein mechanical communication with the ball screws (216 a, 216 b). Theactuators (210 a, 210 b) power the ball screws (216 a, 216 b) whichcause the ball nuts (218 a, 218 b) to translate along the axis of theball screws (216 a, 216 b). Accordingly, the translation ‘d’ and pitch‘a’ of the working portion 204 may be adjusted depending on the positionof each ball nut (218 a, 218 b) on their corresponding ball screw (216a, 216 b). A linear guide 222 may further constrain and guide the motionof the linear rails (208 a, 208 b) in the translational direction ‘d’.

Computing System and Tracking System

With reference back to FIG. 1, the computing system 102 generallyincludes hardware and software for executing a surgical procedure. Inparticular embodiments, the computing system 102 provides actuationcommands to the actuators (210 a, 210 b) to control the position andorientation (POSE) of the tool 206. The computing system 102 can thusmaintain the tool axis 207 with a virtual plane defined in a surgicalplan independent of the POSE of the hand-held portion 202.

The computing system 102 in some inventive embodiments includes: adevice computer 108 including a processor; a planning computer 110including a processor; a tracking computer 111 including a processor,and peripheral devices. Processors operate in the computing system 102to perform computations associated with the inventive system and method.It is appreciated that processor functions are shared between computers,a remote server, a cloud computing facility, or combinations thereof.

In particular inventive embodiments, the device computer 108 may includeone or more processors, controllers, and any additional data storagemedium such as RAM, ROM or other non-volatile or volatile memory toperform functions related to the operation of the surgical device 104.For example, the device computer 108 may include software, data, andutilities to control the surgical device 104 such as the POSE of theworking portion 204, receive and process tracking data, control thespeed of the motor 205, execute registration algorithms, executecalibration routines, provide workflow instructions to the userthroughout a surgical procedure, as well as any other suitable software,data or utilities required to successfully perform the procedure inaccordance with embodiments of the invention.

The device computer 108, the planning computer 110, and the trackingcomputer 111 may be separate entities as shown, or it is contemplatedthat their operations may be executed on just one or two computersdepending on the configuration of the surgical system 100. For example,the tracking computer 111 may have operational data to control thedevice 104 without the need for a device computer 108. Or the devicecomputer 108 may include operational data to plan to the surgicalprocedure with the need for the planning computer 110. In any case, theperipheral devices allow a user to interface with the surgical system100 and may include: one or more user interfaces, such as a display ormonitor 112; and various user input mechanisms, illustratively includinga keyboard 114, mouse 122, pendent 124, joystick 126, foot pedal 128, orthe monitor 112 may have touchscreen capabilities.

The planning computer 110 is preferably dedicated to planning theprocedure either pre-operatively or intra-operatively. For example, theplanning computer 110 may contain hardware (e.g. processors,controllers, and memory), software, data, and utilities capable ofreceiving and reading medical imaging data, segmenting imaging data,constructing and manipulating three-dimensional (3D) virtual models,storing and providing computer-aided design (CAD) files, planning thePOSE of the implants relative to the bone, generating the surgical plandata for use with the system 100, and providing other various functionsto aid a user in planning the surgical procedure. The planning computeralso contains software dedicated to defining virtual planes with regardsto embodiments of the invention as further described below. The finalsurgical plan data may include an image data set of the bone, boneregistration data, subject identification information, the POSE of theimplants relative to the bone, the POSE of one or more virtual planesdefined relative to the bone, and any tissue modification instructionssuch as those tissue modifications described in PCT Pub. US2015/051713wherein the tool 206 may be an oscillating saw for creating planar bonecuts. The device computer 108 and the planning computer 110 may bedirectly connected in the operating room, or may exist as separateentities. The final surgical plan is readily transferred to the devicecomputer 108 and/or tracking computer 111 through a wired or wirelessconnection in the operating room (OR); or transferred via anon-transient data storage medium (e.g. a compact disc (CD), a portableuniversal serial bus (USB drive)) if the planning computer 110 islocated outside the OR. As described above, the computing system 102 mayact as a single entity, with multiple processors, capable of performingthe functions of the device computer 108, the tracking computer 111, andthe planning computer 110.

The computing system 102 may accurately maintain the tool axis 207 in3-D space based on POSE data from the tracking system 106 as shown inFIG. 1. The tracking system 106 generally includes a detection device todetermine the POSE of an object relative to the position of thedetection device. In a particular embodiment, the tracking system 106 isan optical tracking system as described in U.S. Pat. No. 6,061,644,having two or more optical receivers 116 to detect the position offiducial markers arranged on rigid bodies. Illustrative examples of thefiducial markers include: an active transmitter, such as an LED orelectromagnetic radiation emitter; a passive reflector, such as aplastic sphere with a retro-reflective film; or a distinct pattern orsequence of shapes, lines or other characters. A set of fiducial markersarranged on a rigid body is referred to herein as a fiducial markerarray (120 a, 120 b, 120 c, 212), where each fiducial marker array (120a, 120 b, 120 c, 212) has a unique geometry/arrangement of fiducialmarkers, or a unique transmitting wavelength/frequency if the markersare active LEDS, such that the tracking system 106 can distinguishbetween each of the tracked objects. In a specific embodiment, thefiducial marker arrays (120 a, 120 b, 120 c, 212) include three or moreactive emitters or passive reflectors uniquely arranged in a knowngeometry on each rigid body.

The tracking system 106 may be built into a surgical light 118, locatedon a boom, stand, or built into the walls or ceilings of the operatingroom. The tracking system computer 111 includes tracking hardware,software, data, and utilities to determine the POSE of objects (e.g.bones such as the femur F and tibia T, the surgical device 104) in alocal or global coordinate frame. The POSE of the objects is referred toherein as POSE data, where this POSE data is readily communicated to thedevice computer 108 through a wired or wireless connection.Alternatively, the device computer 108 may determine the POSE data usingthe position of the fiducial markers detected directly from the opticalreceivers 116.

The POSE data is determined using the position of the fiducial markersdetected from the optical receivers 116 and operations/processes such asimage processing, image filtering, triangulation algorithms, geometricrelationship processing, registration algorithms, calibrationalgorithms, and coordinate transformation processing.

POSE data from the tracking system 106 is used by the computing system102 to perform various functions. For example, the POSE of a digitizerprobe 130 with an attached probe fiducial marker array 120 c may becalibrated such that tip of the probe is continuously known as describedin U.S. Pat. No. 7,043,961. The POSE of the tip or axis of the tool 206may be known with respect to the device fiducial marker array 212 usinga calibration method as described in Int'l Pat. App. No. WO 2016/141378.Registration algorithms are readily executed using the POSE data todetermine the POSE and/or coordinate transforms between a bone, asurgical plan, and a surgical system. For example, in registrationmethods as described in U.S. Pat. Nos. 6,033,415 and 8,287,522, pointson a patient's bone may be collected using a tracked digitizer probe totransform the coordinates of a surgical plan, coordinates of the bone,and the coordinates of a surgical device, The bone may also beregistered using image registration as described in U.S. Pat. No.5,951,475. The coordinate transformations may be continuously updatedusing the POSE data from a tracking system tracking the POSE of the bonepost-registration and the surgical device.

It should be appreciated that in certain inventive embodiments, othertracking systems are incorporated with the surgical system 100 such asan electromagnetic field tracking system, ultrasound tracking systems,accelerometers and gyroscopes, or a mechanical tracking system. Thereplacement of a non-mechanical tracking system with other trackingsystems should be apparent to one skilled in the art. In specificembodiments, the use of a mechanical tracking system may be advantageousdepending on the type of surgical system used such as the one describedin U.S. Pat. No. 6,322,567 assigned to the assignee of the presentapplication and incorporated by reference in its entirety.

In the surgical system 100, an optical tracking system 106 with opticalreceivers 116 is used to collect POSE data of the femur and tibia duringtotal knee arthroplasty. The distal femur F and proximal tibia T areexposed as in a typical TKA procedure. Tracking arrays 120 a and 120 bare attached thereto and the femur F and tibia T are subsequentlydigitized and registered to a surgical plan. The POSE of the femur F andtibia T are tracked in real-time by the tracking system 106 so thecoordinate transformation between the surgical plan and the surgicaldevice are updated as the bones and surgical device move in theoperating space. Therefore, a relationship between the POSE of the tool206 and the POSE of any coordinates defined in the surgical plan may bedetermined by the computing system 102. In turn, the computing system102 can supply actuation commands to the actuators (210 a, 210 b) inreal-time to accurately maintain the tool axis 207 to the definedcoordinates.

Additionally, user input mechanisms, such as the trigger 214 or footpedal 128, may be used by the user to indicate to the computing system102 that the tool axis 207 needs to be maintained to other coordinatesdefined in a surgical plan. For example, the tool axis 207 may bemaintained in a first defined plane, and the user may step on the footpedal 128 to relay to the computing system 102 that the tool axis 207needs to be maintained in a second defined plane.

Surgical Planning and Execution for a Total Knee Arthroplasty (TKA)Application

The surgical plan is created, either pre-operatively orintra-operatively, by a user using planning software. The planningsoftware may be used to a generate three-dimensional (3-D) models of thepatient's bony anatomy from a computed tomography (CT), magneticresonance imaging (MRI), x-ray, ultrasound image data set, or from a setof points collected on the bone intra-operatively. A set of 3-D computeraided design (CAD) models of the manufacturer's prosthesis arepre-loaded in the software that allows the user to place the componentsof a desired prosthesis to the 3-D model of the boney anatomy todesignate the best fit, position and orientation of the implant to thebone. For example, with reference to FIG. 3, a 3-D model of thepatient's distal femur 302 and a 3-D model of the femoral prosthesis 304are shown. The final placement of the femoral prosthesis model 304 onthe bone model 302 defines the bone cut planes (shaded regions of thebone model 302) where the bone is cut intra-operatively to receive theprosthesis as desired. In TKA, the planned cut planes generally includethe anterior cut plane 306, anterior chamfer cut plane 308, the distalcut plane 310, the posterior chamfer cut plane 312, the posterior cutplane 314 and the tibial cut plane (not shown).

The surgical plan contains the 3-D model of the patient's operative bonecombined with the location of one or more virtual planes 414. Thelocation of the virtual plane(s) 414 is defined by the planning softwareusing the position and orientation (POSE) of one or more planned cutplanes and one or more dimensions of a cutting guide or alignment guide.Ultimately, the location of the virtual plane(s) 414 is defined to aidin the placement of a cutting guide such that one or more guide slots ofthe cutting guide are in the correct POSE to accurately guide a saw increating the bone cuts. Embodiments of the various inventive cuttingguides, alignment guides, defining of the virtual planes, and use of thebone pins are further described in detail below.

In general, embodiments of the inventive cutting guides and alignmentguides disclosed herein may be made of a rigid or semi-rigid material,such as stainless steel, aluminum, titanium, polyetheretherketone(PEEK), polyphenylsulfone, acrylonitrile butadiene styrene (ABS), andthe like. Embodiments of the cutting guides and alignment guides may bemanufactured using appropriate machining tools known in the art.

Distal Cutting Guide, Alignment Guide and N-In-1 Cutting Block

A particular inventive embodiment of a cutting guide to accuratelycreate the planned distal cut plane 310 is the universal distal cuttingguide 400 as depicted in FIG. 4A and FIG. 4B. The distal cutting guide400 includes a guide portion 402 and an attachment portion 404. Theguide portion 402 includes a guide slot 406 and a bottom surface 410.The guide slot 406 is for guiding a surgical saw in creating the distalcut plane 416 on the femur. The bottom surface 410 abuts against one ormore bone pins 412 that are placed on the bone. The attachment portion404 and the guide portion 402 clamp to the bone pins 412 using fasteners408 as shown in FIG. 4B and FIG. 4D.

A surgical system is used to place the longitudinal axis of the bonepins 412 on a virtual pin plane 414. In a particular embodiment, the2-DOF surgical system 100 is used, wherein the tool 206 of the surgicaldevice 104 is a drill bit rotated by the motor 205. As the usermanipulates the surgical device 104, the computing system suppliesactuation commands to the actuators to align the tool axis 207 with thevirtual pin plane 414.

The virtual pin plane 414 is defined in the surgical plan by theplanning software using the POSE of the planned distal cut plane 310,and the distance between the guide slot 406 and the bottom surface 410of the guide portion 402. The planning software may also use the knownwidth of the bone pins 412. For example, the pin plane 414 can bedefined by proximally translating the planned distal cut plane 310 bythe distance between the guide slot 406 and the bottom surface 410 ofthe distal cutting guide 400. The software may further proximallytranslate the planned distal cut plane 310 by an additional half widthof the pins 412. Therefore, when the cutting guide 400 is clamped to thebone pins 412, the guide slot 406 is aligned with the planned distal cutplane 310.

The user or the computing system 102 may activate the motor 205 whenproperly aligned with the pin plane 414 to drill pilot holes for thepins 412. The pins 412 are then drilled into the pilot holes using astandard drill. In a specific embodiment, the tool 206 is the pin 412,wherein the pin 412 is attached to the motor 205 of the surgical device104 and drilled directly into the bone on the pin plane 414. At leasttwo bone pins 412 may be drilled on the pin plane 414 to constrain thedistal cutting guide 400 in the proper position and orientation whenclamped to the pins 412 however three or more bone pins 412 can be usedfor further stability.

There are multiple advantages to using the 2-DOF surgical system 100 toaccurately place the bone pins 412. For one, the surgical device 104 isactuating in real-time, therefore the user is actively guided to thePOSE of the pin plane 412. In addition, the correct position andorientation of the bone pins 412 is accurately maintained regardless ofthe surgeon's placement of the hand-held portion 202 of the 2-DOFsurgical system 100.

One main advantage of the cutting guide 400 is its universality becausethe cutting guide 400 may be used for any type of implant and any typeof patient. This is particularly advantageous, because the universaldistal cutting guide 400 can be sterilized and re-used for multiplesurgeries, greatly reducing the cost of TKA, which otherwise requireseither patient specific cutting guides or implant specific cuttingguides for each surgery.

The advantageous part of using pin planes 414, rather than defining aspecific location for the bone pins 412, is the user can place thelongitudinal axes of the pins 412 in any arbitrary orientation andposition on the virtual pin plane 414 and still attach the cutting guide400 such that the guide slot 406 is accurately aligned with the planneddistal cut plane 310. This greatly reduces the operational time of theprocedure. In addition, the user can avoid any particular landmarkscoincident with the virtual pin plane 414 if so desired.

After the cutting guide 400 is assembled on the bone pins 412, the usercan saw the distal cut 416 on the femur F by guiding a surgical sawthrough the guide slot 406. Subsequently, the bone pins 412 and cuttingguide 400 are removed from the bone to create the remaining bone cuts.

In a particular embodiment, with respect to FIGS. 5A-5D, a prior art4-in-1 cutting block 500 is used to create the remaining bone cuts. FIG.5A is a perspective view of the 4-in-1 cutting block, FIG. 5B is a sideelevation view thereof, FIG. 5C is a top plan view thereof, and FIG. 5Dis a bottom plan view thereof. The 4-in-1 cutting block 500 may be madeof materials similar to that of the distal cutting guide 400. The 4-in-1cutting block 500 is manufactured to include a body 502, a posteriorguide slot 504, a posterior chamfer guide slot 506, an anterior chamferguide slot 508, and an anterior guide slot 510. The cutting block 500also includes two pegs 512 to fit into pilot holes to be drilled on thedistal cut plane 416, and two pin securing guides 514 to receive pins412′ to secure the cutting block 500 to the femur F. Although a 4-in-1cutting block 500 is described herein, it should be appreciated that anyN-in-1 cutting block for creating additional cut-planes on the bone maybe aligned and assembled on the bone using the embodiments describedherein. An N-in-1 cutting block can account for femoral prostheseshaving greater than 5 planar contact surfaces (for reference andclarity, the femoral prosthesis 304 shown in FIG. 3 has 5 planar contactsurfaces such as the posterior contact surface 318 that mates with theposterior cut plane 314 as shown in FIG. 3).

The 4-in-1 cutting block 500 may be aligned on the bone using analignment guide. A particular embodiment of the alignment guide is aplanar alignment guide 600 as shown in FIG. 6A and FIG. 6B. FIG. 6A is aperspective view of the planar alignment guide 600, and FIG. 6B is a topplan view of thereof. The planar alignment guide 600 includes a body602, and two holes 604 integrated with the body 602. The body 602includes a bottom portion 606 adapted to fit in a channel 800 (shown inFIG. 8A) to be milled on the distal cut plane 416. The distance betweenthe centers of the holes 604 correspond to the distance between thecenters of the pegs 512 of the 4-in-1 block 500.

With reference to FIGS. 7A and 7B, a particular embodiment of thealignment guide is an offset alignment guide 700. FIG. 7A is aperspective view of the alignment guide 700, and FIG. 7B is a bottomplan view thereof. The alignment guide 700 includes a body 702, at leastone ridge 704 at the edge and extending from the body 702, and two holes604′ bored through the body 702, where the two holes 604′ are located aknown distance from the ridge 604. The distance between the centers ofthe two holes 604′ correspond to the distance between the pegs 512 ofthe 4-in-1 cutting block 500. The at least one ridge 704 is adapted tofit in a channel 800 (shown in FIG. 8A) to be milled on the distal cutplane 416.

The location for inserting the pegs 512 of the 4-in-1 cut block 500 onthe distal cut plane 310 is determined based on the planned size andlocation of the prosthesis such that the guide slots of the 4-in-1cutting block 500 align with the remaining bone cut planes. The planningsoftware can define a virtual channel plane in the surgical plan, inwhich a channel 800 will be milled to receive the alignment guide (600,700). In a particular embodiment, the channel plane is defined by aplane that is perpendicular to the distal cut plane and aligned with themedial-lateral direction of the prosthesis. In another embodiment, thechannel plane is defined based on the POSE of the planned anterior cutplane 306 or posterior cut plane 314, and the location of the pegsrequired to align the guide slots for the remaining bone cuts. Forexample, if the planar alignment guide 600 is used, the planningsoftware can define a virtual channel plane by anteriorly translatingthe planned posterior cut plane 314 to the location of the center of thepegs 512 of the 4-in-1 cutting block 500. If the offset alignment guide700 is used, then, the virtual channel plane is defined by anteriorlytranslating the planned posterior cut plane 314 to the location of thepegs 512, and then posteriorly/anteriorly translating the planned planeby the known distance between the center of the holes 604′ and the ridge704.

The virtual channel plane defined in the surgical plan is used to createa channel 800 on the distal cut plane 416 formed on the femur F with asurgical system as shown in FIGS. 8A-8D. In a particular embodiment, the2-DOF surgical system 100 is used wherein the tool 206 of the surgicaldevice 104 is actuated such that the tool axis 207 remains substantiallycoincident with the channel plane. To mill the channel 800, the tool 206is a bone cutting tool such as an end mill, burr, a rotary cutter, or anoscillating saw as described in PCT Pub. US2015/051713. The tool 206 mayfurther include a sleeve to prevent the tool 206 from cutting thechannel 800 too deep. After the channel 800 is milled, an alignmentguide (600, 700) is placed in the channel 800, whereby the holes (604,604′) are aligned with the position for the pegs 512 of the 4-in-1cutting block 500. When using the planar alignment guide 600, the bottomportion 606 of the body 602 fits directly in the channel 800. When usingthe offset alignment guide 700, the ridge 704 fits directly into thechannel 800 as shown in FIGS. 8C and 8D. In both cases, a standard drillis then used to drill pilot holes for the pegs 512 by drilling throughthe holes (600, 604′) of the alignment guide (600, 700).

After the holes for the pegs 512 have been drilled, the alignment guide(600, 700) is removed from the femur F. The 4-in-1 cutting block 500 isattached to the femur F by placing the pegs 512 in the drilled pilotholes. The remaining four bone cuts on the femur F are created using asurgical saw guided by the guide slots (504, 506, 508, 510) of the4-in-1 cutting block 500. The 4-in-1 block 500 is then removed, and thefemoral prosthesis can be fixed to the femur F in a conventional manner.

A particular advantage in using the offset alignment guide 700 asopposed to the planar alignment guide 600, is the created channel 800 toreceive the ridge 704 can be removed with one of the four planar cuts,depending on the distance between the ridge 704 and the holes 604′. Ingeneral, the use of the channel plane with an alignment guide (600, 700)is advantageous because the position of the cutting block 500 in themedial-lateral direction does not need to be precise on the distal cutplane 416 as long as the guide slots (504, 506, 508, 510) of the 4-in-1cutting block 500 span enough of the bone to create the remaining bonecuts. Additionally, by using a surgical system, the channel can bequickly and accurately created. In combination, all of these are highlyadvantageous over the traditional cutting alignment guides because thereis no need to reference a monitor if passive navigation was otherwiseused, there is no need to locate multiple anatomical landmarks to drillthe holes for the pegs of a 4-in-1 block, and the overall surgical timeis reduced.

Distal Cutting Guide with Alignment Guide

In a particular embodiment of a cutting guide, a distal cutting andalignment guide 900 is illustrated in FIG. 9A and FIG. 9B. A frontperspective view of the distal cutting guide 900 is shown in FIG. 9A,and a rear perspective view thereof is shown in FIG. 9B. The distalcutting and alignment guide 900 includes a guide portion 902 and anattachment portion 904. The guide portion 902 may be in the shape of aninverted “L”, with a distal guide slot 906 and a pair of holes 908 boredthrough. The distance between the centers of the two holes 908correspond to the distance between the pegs 512 of the 4-in-1 block 500.The guide portion 902 also includes an abutment face 912 adapted to abutagainst alignment pins 914. The attachment portion 904 attaches to theguide portion 902 with fasteners 910 to clamp the distal cutting andalignment guide 900 to the bone pins 912.

The planning software defines two virtual planes to accurately place thedistal cutting and alignment guide 900 to the femur F. A first pin planeis defined such that the guide slot 906 aligns with the planned distalcut plane 310 when the cutting guide 900 is assembled to the bone pins912. A second pin plane is defined such that when the face 912 abutsagainst the alignment pins 914 inserted with a second pin plane, theholes 908 align with the POSE for the pegs 512 of the 4-in-1 cuttingblock 500. For example, in FIG. 9C, the first pin plane is defined forthe bone pins 912 and the second pin plane is defined for the alignmentpins 914. The second pin plane is defined in the planning software asfollows: 1) a plane is defined perpendicular to the planned distal cutplane 310 and parallel with the planned position for the pegs 512, and2) that plane is then posteriorly translated by the distance between thecenters of the holes 908 and the face 912 of the distal cutting andalignment guide 900. Therefore, when the face 912 abuts against thealignment pins 914, the holes 908 are accurately aligned in theanterior/posterior direction and internal-external rotation.

The bone pins 912 and alignment pins 914 are accurately placed on thefirst and second pin planes using a surgical system as described above.The cutting guide 900 is then assembled to the femur F, wherein the face912 abuts against the alignment pins 914 as shown in FIG. 9D. Before thesurgeon creates the distal cut 416, two pilot holes are drilled throughthe holes 908. The alignment pins 914 are removed and the distal cut 416is made by guiding a surgical saw through the guide slot 906. Thecutting guide 900 is removed from the femur F, and the 4-in-1 guideblock can be directly assembled in the pilot holes to aid in creatingthe remaining cuts.

Slot Alignment Guide

In a particular embodiment of an alignment guide, a slot alignment guide1000 is shown in FIG. 10A and FIG. 10B. FIG. 10A is a perspective viewof the slot alignment guide 1000, and FIG. 6B is a top plan viewthereof. The slot alignment guide 1000 includes two holes 1002, and apin receiving slot 1004. The slot alignment guide 1000 may furtherinclude a lip 1006. The distance between the centers of the two holes1002 correspond to the distance between the pegs 512 of the 4-in-1 block500. The pin receiving slot 1004 is of sufficient width to be receivedon bone pins 1008. The distance between the center of the slot 1004 andthe holes 1002 are known to define a virtual pin plane for the bone pins1008.

The slot alignment guide 1000 may be used if the cancellous bone on thedistal surface 416 of the femur F is particularly soft, weak, or moreflexible. In these cases, the planar alignment guide 600 or the offsetalignment guide 700 in the channel 800 may become misaligned due to theflexible nature of this cancellous bone. Therefore, bone pins 1008 maybe inserted on the channel plane as defined above. The bone pins 1008are aligned and inserted on the channel plane using the methodspreviously described as shown in FIG. 10C. A ring 1010 such as a washeror spacer may be placed on the bone pins 1008 to further protect thedistal surface 416 of the femur F. The pin receiving slot 1004 of theslot alignment guide 1000 is placed on the bone pins 1008. The lip 1006may interact with the ring 1010 such that the alignment guide 1000 liesflat on the distal surface 416 of the femur F. A user may then drillpilot holes through the holes 1002 using a standard drill. The alignmentguide 1000 and the bone pins 1008 are removed from the femur F and thepegs 512 of the 4-in-1 guide block 500 is assembled in the pilot holesto aid in creating the remaining bone cuts.

It should be appreciated that the 4-in-1 block may have other features,other than the pegs 512, to interact and attach with the distal cutsurface 416 of the femur F. The pegs 512 may instead be a body extrudingfrom the bottom surface of the 4-in-1 block 500 and adapted to fit in acorresponding shape created on the distal cut surface 416. The extrudingbody may have a variety of shapes including an extruded rectangle,triangle, the shapes manufactured for a keel of a tibial base plateimplant, and any other extruding body/bodies. Therefore, the alignmentguides described herein may have the same corresponding shape, insteadof the holes (604, 604′, 908, and 1004), to guide a user in creatingthat shape on the distal cut surface 416 so the 4-in-1 block can beaccurately placed thereon.

Clamp Alignment Guide

With reference to FIGS. 16A-17C, a clamp alignment guide (1600, 1700) isused to aid in the alignment of an N-in-1 cutting block on the femur.The clamp alignment guides (1600, 1700) are configured to clamp ontotheir own set of pins in a POSE that permits a user to accurately createthe pilot holes for the cutting block pegs 512. In a particularembodiment, with reference to FIGS. 16A-16E, a referencing clampalignment guide 1600 and the use thereof is shown. The referencing clampalignment guide 1600 includes a guide portion 1602 and a clampingportion 1604. The guide portion 1602 has a pair of referencing feet 1606that reference a top surface 409 of the universal distal cutting guide400′, and two or more holes 1608 spaced a distance apart correspondingto the distance between the pegs 512 of a cutting block.

In general, a virtual pin plane for the clamp alignment guides (1600,1700) is defined by: 1) defining a plane perpendicular to the planneddistal cut plane 310 and parallel with the planned position for the pegs512; 2) posteriorly translating that plane by the known distance betweenthe centers of the holes 1608 and a bottom surface 1609 of the guideportion 1602; and 3) further posteriorly translating that plane by anadditional half-width of the pins 1610.

Use of the reference clamp alignment guide 1600 is shown with respect toFIGS. 16C and 16D. A universal cut guide 400′ is first assembled on thefemur F as described above. The pins 1610 are positioned on the virtualpin plane using a surgical system, such as the 2-DOF surgical system100. The clamp alignment guide 1600 is assembled on the pins 1610 withthe feet 1606 referencing the top surface 409 of the universal cut guide400′. The user then drills the pilot holes for the cutting block pegs512 using the holes 1608 as a guide. After which, the clamp alignmentguide 1600 and pins 1610 are removed from the bone and the user createsthe distal cut via the guide slot 406. Subsequently, the distal cutguide 400′ and distal pins 412 are removed from the bone, the cuttingblock pegs 512 are inserted in the pilot holes, and the remaining cutplanes are created on the femur.

There is one issue a user may encounter when using the clamp alignmentguides (1600, 1700). The drill and drill bit for creating the N-in-1pilot holes need to have sufficient clearance so as to not interferewith the placement of the pins 1610, while also permitting the drill bitto traverse all of the bone distal to the distal cut plane and create ahole beyond the distal cut plane that is deep enough to fully receivethe cutting block pegs 512. In a particular embodiment, with referenceto FIG. 16E, this problem is solved using a stepped diameter drill bit1617. FIG. 16E depicts the distal cut guide 400′ and reference clampalignment guide 1600 assembled on the bone, and a drill 1618 driving astepped diameter drill bit 1617 placed through the guide holes 1608.Because the exact distance between the planned distal cut plane 310 andthe top of the guide 1614 is known (this is geometrically known becausethe distance from i) the guide slot 406 and the distal guide's topsurface 409 is known, and ii) the distance from the bottom of thereferencing feet 1606 stabilized on the top surface 409, to the top ofthe guide 1614 is also known, therefore i+ii=the distance between thetop of the guide 1614 and the planned cut plane 310), a drill bit 1617having a stepped diameter can simultaneously clear the length of thepins 1610 and also set the engagement in the bone beyond the planneddistal cut plane 310 so the user does not have to determine how deep todrill. Here the drill bit 1617 has a distal portion 1619 having adiameter less than a proximal portion 1620. The distal portion 1619 hasa diameter that fits through the guide holes 1608 and large enough tocreate a hole for receiving the cutting block pegs 512. The distalportion 1619 has a length capable of traversing the bone distal of theplanned distal cut plane 310 and extend beyond the distal cut plane 310enough to create a pilot hole deep enough to fully receive the pegs 512.The proximal portion 1620 has a diameter larger than the diameter of theguide holes 1608 and a length that ensures the bulky drill 1618 does notinterfere with pins 1610. In another embodiment, to solve this clearanceissue, the drill 1618 is tracked by a tracking system and a monitorprovides visual feedback to the user. When the tip of the drill extendsbeyond a certain depth (e.g. breaks the planned distal cut plane 310),the monitor displays this information and/or provides depth information.

In a specific embodiment, with reference to FIGS. 17A-17C, a plane clampalignment guide 1700 is used to aid in the creation of the pilot holesto receive the cutting block pegs 512. The plane alignment guide 1700 isplaced directly on the distal cut plane 416 and includes a guide portion1702 and a clamping portion 1704. The guide portion 1700 includes two ormore holes 1706 similar to the reference clamp alignment guide 1600. Theguide 1700 may further include a projection 1708 to increase the contactsurface area between the guide 1700 and the distal cut surface 416 toincrease the stability of the guide on the distal surface 416.Accordingly, the bottom surface 1712 of the plane alignment guide 1700is flat to mate with the planar distal cut surface 416. Fasteners 1710or a clamping mechanism allows the plane guide 1700 to assemble to thepins 1714 inserted on the bone.

The procedure for using the plane alignment guide 1700 is as follows.The user first creates the distal cut using a universal distal cuttingguide 400. The user then inserts pins 1714 on a virtual pin plane, wherethe virtual pin plane is defined as described above for the referencingclamp alignment guide 1600. The pins 1714 are inserted directly on thedistal cut surface 416 as shown in FIG. 17C. The plane alignment guide1700 is then clamped to the pins 1714 where the bottom surface 1712 ofthe guide 1700 lies flush with the distal cut surface 416. The userdrills the pilot holes for the pegs 512 using the holes 1706 as a guide.Subsequently, the pins 1714 and the plane alignment guide 1700 areremoved, the pegs 512 of an N-in-1 cutting block are placed in the pilotholes, and the remaining cut planes are created. The clearance issuedescribed above for the reference alignment guide 1600 can be readilysolved in a similar manner for the plane alignment guide 1700.

5-DOF Chamfer Guide

In a specific embodiment of the cutting guide, a 5-DOF chamfer cuttingguide 1100 is shown in FIGS. 11A-11E. FIG. 11A is a perspective view ofthe top of the chamfer cutting guide 1100, FIG. 11B is a perspectiveview of the bottom thereof, FIG. 11C is a top plan view, FIG. 11D is afront elevation view, and FIG. 11E is a side elevation view. The chamfercutting guide 1100 includes a guide body 1102 in the shape of aninverted “L”. The guide body 1102 includes a first attachment slot 1104a, a second attachment slot 1104 b, a distal guide slot 1106, ananterior guide slot 1108, and a chamfer guide slot 1110. One side of theattachment slots 1104 is open, so the chamfer cutting guide 1100 canslide onto the bone pins. The attachment slot opening is best visualizedin FIG. 11D on the right side of the attachment slots 1104.

The planning software defines the location of 5-DOF chamfer cuttingguide 1100 in the location necessary to place the guide slots in thecorrect position and orientation to accurately execute the planned cutplanes. The surgical plan also includes two virtual pin planes (1202 a,1202 b, as shown in FIGS. 12A-12B), on which bone pins (1204 a, 1204 b)are placed that are defined relative to the cut planes; the two planeshave an intersection axis that is parallel to all of the cut planes. Thevirtual pin planes (1202 a, 1202 b) may be defined using the knowndimensions of the chamfer cutting guide 1100, and the POSE of theplanned cut planes. For example, the planning software knows theposition and orientation of the attachment slots 1104 with respect tothe guide slots. Using these dimensions the planning software may definea first pin plane 1204 a and a second pin plane 1204 b. By defining twovirtual pin planes (1202 a, 1202 b) with four or more pins, 5 degrees offreedom are constrained, which is sufficient to perform a TKA procedureusing a surgical saw if the unconstrained degree of freedom is in themedial-lateral direction, which is parallel to all of the cut planes.

A surgical system, such as the one described above, is then used toplace the bone pins (1204 a. 1204 b) substantially coincident with thevirtual pin planes (1202 a, 1202 b). Once again, the pins 1204 can beinserted at an arbitrary position and orientation on a virtual pinplane. The attachment slots 1104 of the chamfer cutting guide 1100 slideover the bone pins (1204 a. 1204 b) as shown in FIG. 12C. The user thencreates the distal cut plane, anterior cut plane, posterior cut plane,and the chamfer cut planes by guiding a surgical saw through therespective guide slots. The chamfer guide 1100 and the bone pins 1204are then removed. A second cut guide (not shown), which fits against thedistal and posterior cut surfaces can guide the anterior cut usingsimilar embodiments of the cutting guides, pin planes, and bone pins asdescribed herein.

Pin Alignment Guide

In a particular embodiment of an alignment guide, a pin alignment guide1300 is shown in FIG. 13A and FIG. 13B. The pin alignment guide 1300includes a tubular body 1302 and fins 1304 extruding outwardly from thetubular body 1302. The pin alignment guide 1300 aids a user in aligningbone pins for use with a cutting guide that requires the bone pins to beplaced a specific distance apart. For example, the cutting guide 1400shown in FIGS. 14A and 14B includes a guide slot 1402, and two holes1404 that receive bone pins placed a specific distance apart.

To use the pin alignment guides 1300, with respect to FIG. 15A, at leasttwo perpendicular channel planes are defined in the planning software. Afirst channel plane, to create a first channel 1502 on the bone, isdefined as described above using the planned distal cut plane 310 andthe distance between the guide slot 1402 and the center of the holes1404. A second channel plane, to create a second channel 1504 on thebone, is defined perpendicular to the first channel plane. A thirdchannel plane is defined perpendicular to the first channel plane andmedially/laterally translated by the distance between the centers of theholes 1404 of the cutting guide 1400. The channels (1502, 1504) areprecisely milled on the bone using a surgical system as described above.

The intersection of the first channel 1502 and the second channel 1504(shown at 1506), receives the pin alignment guide 1300 as shown in FIG.15B, wherein the fins 1304 fit directly into the channels. A user canthen drill a pilot hole, or a bone pin directly through the tubular body1302 of the pin alignment guide 1300. The procedure is repeated to placeany additional bone pins on the bone. Subsequently, the holes 1404 ofthe cutting guide 1400 are placed on the bone pins, and the bone cut iscreated as planned. It should be appreciated that this technique cansimilarly be used for other cutting guides. For example, the pinalignment guide technique can be used to create pilot holes on thedistal cut 416 of the femur F for the pegs 512 of a 4-in-1 block 500.

Tibial Cut Plane

The tibial cut plane may be created using similar embodiments asdescribed above and should be apparent to one skilled in the art afterreading the subject matter herein.

In a particular embodiment, the tibial cut guide may be aligned invarus-valgus rotation, internal-external rotation, flexion-extensionrotation, and proximal-distal position. The anterior-posterior positionis not important. The tibial cut guide is positioned using two or morepins positioned on two planes that have an intersection axis that isaligned with the planned anterior-posterior direction. For example, twoplanes oriented±45° in varus-valgus, such that when the guide is placedon the pins, all degrees of freedom except the anterior-posterior areconstrained.

Example: Distal Cutting Guide, Alignment Guide and 4-in-1 Block

Testing was conducted on femoral and tibia saw bones using the 2-DOFsurgical system 100, the universal distal cutting guide 400, the offsetalignment guide 700 and the 4-in-1 block 500. Artificial ligaments wereattached between the saw bones to mimic the kinematics of the knee. Thepurpose of the testing was to assess the overall time required to createthe planar cuts on the femoral saw bone, referred to hereafter as femur.The timing began prior to fixing the femoral tracking array 120 b andended once the last cut plane on the femur was completed.

To begin, the femoral tracking array 120 b was fixed to the lateral sideof the femur. A tracked digitizer probe 130 was used to collect variouspoints on the distal femoral surface. The collected points were used toregister the POSE of the femur to a surgical plan. The 2-DOF surgicaldevice 104 was used to drill two holes in the virtual pin plane 414, thevirtual pin plane 414 being defined in the planning software prior totesting. A standard drill was then used to insert pins 412 in thedrilled holes. The universal distal cutting guide 400 was clamped to thepins 412 and the distal cut 416 was created using a surgical saw guidedthrough the slot 406 of the distal cutting guide 400. The distal cuttingguide 400 and pins 412 were then removed from the femur.

The 2-DOF surgical device 104 was then used to mill a channel 800 on thedistal cut surface 416 along the virtual channel plane, the virtualchannel plane being defined in the planning software prior to testing.The ridge 704 of the offset alignment guide 700 was placed in thechannel 800 and a standard drill was used to drill two holes on thedistal surface 416 guided by the two holes 604′ of the offset alignmentguide 700. The offset alignment guide 700 was removed from the channel800 and the pegs 512 of the 4-in-1 block 500 were placed in the twodrilled holes. The remaining four planar cuts were created using asurgical saw guided by the guide slots (504, 506, 508, and 510) of the4-in-1 block 500. The recorded time from femoral tracking array 120 bfixation to the creation of the final cut plane was approximately 18minutes.

It is worthy to note, that during testing the standard drill had lostpower and required charging. The timing was not stopped during thecharging step. It is presumed that an experienced surgeon could executethis testing procedure in approximately 10 to 15 minutes.

Articulating Pin-Driving Device

The articulating device 104 of the 2-DOF surgical system 100 describedabove can accurately align a tool/pin to be coincident with one or morevirtual planes. However, the surgeon still has to manually advance thedevice 104 towards the bone to insert the pin or to create a pilot holefor the pin, which may be uncomfortable for the surgeon. In addition, itis possible that extreme or sudden movements by the surgeon or bonewhile operating the device may introduce small errors in the pinalignment. A contributing factor to the extreme or sudden movements maybe a lacking of real-time information, during use, as to thearticulating travel range, or workspace, in which the device operates104 within.

To provide further control and feedback for the user, the 2-DOF surgicaldevice 104 may be modified to include a third pin-drivingdegree-of-freedom, which will be referred to hereinafter as anarticulating pin-driver device 104′. With reference to FIGS. 18A-18C inwhich like reference numerals have the meaning ascribed to that numeralwith respect to the aforementioned figures, a particular embodiment ofthe articulating pin driver device 104′ is shown. In addition to thecomponents of the 2-DOF surgical device 104, the working portion 204′ ofthe articulating pin driver device 104′ further includes componentsconfigured to drive a pin 206′ into a bone. Specifically, with referenceto FIG. 18C, the working portion 204′ includes the motor 205, a motorcoupler 1808, a pin-driving ball screw 1804, a pin holder 1806, and thepin 206′. A specially adapted carriage 1810 is configured to support andcarry the working portion 204′ and may include mechanisms for actuatingthe pin. In some inventive embodiments, the carriage 1810 includes apin-driving ball nut 1812 and connection members 1814 such as holes,bearings, or axle supports to receive a rod, a dowel, or an axel to actas the hinges (220 a, 220 b) that are connected with the first end ofthe linear rails (208 a, 208 b). The motor coupler 1808 couples themotor 205 with the pin-driving ball screw 1804. The pin-driving ballscrew 1804 is in mechanical communication with the pin-driving ball nut1812. The pin holder 1806 connects the pin-driving ball screw 1804 withthe pin 206′. The pin 206′ is removably attached with the pin holder1806 to allow the pin 206′ to remain in the bone when inserted therein.The motor 205 may bi-rotationally drive the pin-driving ball screw 1804and the pin 206′ to advance and drive the pin 206′ into a bone. Thecomponents may further include a motor carriage (not shown) operablyconnected with a motor linear rail (not shown). The motor carriage issecured to the motor 205 to keep the motor 205 from rotating whileallowing the motor 205 to translate along the motor linear rail. Themotor linear rail may extend from the carriage 1810. FIG. 18Aillustrates the pin 206′ in a retracted state and FIG. 18B illustratesthe pin 206′ in an extended state, where the pin 206′ can translate adistance “d2”. An outer guard 1802 may be present to guard the user fromthe actuating mechanisms in the working portion 204′. If an outer guard1802 is present, the guard 1802 may be dimensioned to conceal the entirepin 206′ when the pin 206′ is in the retracted state, or the guard 1802may only conceal a portion of the pin 206′ to allow the user tovisualize the tip of the pin 206′ prior to bone insertion.

In a specific embodiment, the working portion 204′ may include a firstmotor 205 for rotating the pin 206′, and a second motor (not shown) fortranslationally driving the pin 206′. The second motor may rotate a ballscrew or a worm gear that is in communication with an opposing ball nutor gear rack configured with the first motor 205. As the second motorbi-rotationally drives the ball screw or worm gear, the first motor 205and the pin 206′ translate accordingly.

The device computer 108 of the articulating pin driving device 104′ mayfurther include hardware and software to control the pin-driving action.In an embodiment, the device computer 108 includes two motor controllersfor independently controlling the front actuator 210 a and back actuator210 b, respectively, to maintain the POSE of the working portion (204,204′). A third motor controller may independently control the motor 205for driving and rotating the pin 206′ into the bone. In the specificembodiment where a first motor 205 rotates the pin 206′ and a secondmotor (not shown) translates the pin 206′, the device computer 108 mayinclude two separate motor controllers to independently control thefirst motor 205 and the second motor.

In a specific embodiment, with reference to FIGS. 19A-19B, thearticulating device 104′ includes a bone stabilizing member 1902attached or integrated with the hand-held portion 202. The bonestabilizing member 1902 includes bone contacting elements (1904 a, 1904b) which are configured to contact the bone and stabilize the hand-heldportion 202 while the working portion 204′ articulates. The bonecontacting elements (1904 a, 1904 b) may be a flat surface, a pointedprotrusion, or a surface having jagged edges to interact with the boneand stabilize the hand-held portion 202. The bone contacting element(s)(1904 a, 1904 b) project just beyond the working portion 204′ such thatthe element(s) (1904 a, 1904 b) may contact the bone without negativelyimpacting how deep the pin 206′ may be inserted in the bone. When theuser is in the approximate region for driving the pin 206′, the user maystabilize the hand-held portion 202 to the bone via the bone contactingelements (1904 a, 1904 b). With the hand-held portion stabilized, theworking portion 204′ further articulates until the pin 206′ is preciselycoincident with a virtual pin plane. In a specific embodiment, once thepin 206′ aligns with the virtual pin plane 214, the system 100automatically locks the actuators (210 a, 210 b) and activates the motor205 to drive the pin 206′ into the bone. In another embodiment, the useractivates a user input mechanism such as a trigger 214 or a buttonbefore the system 100 either locks the actuators (210 a, 210 b), drivesthe pin 206′, or both. Therefore, the user can anticipate and controlwhen the pin 206′ is driven into the bone. This user input mechanism maysimilarly be used by the user to control the amount of extension orretraction of the pin 206′ in general.

In a particular embodiment, with reference to FIG. 19A, one or moreindicators 1906, such as an LED or a display, is attached or integratedwith the device 104′. The indicator 1906 may be attached to the outerguard 1802, the working portion 204′, or the hand-held portion 202 forexample. The indicator(s) 1906 provide feedback to the user as to acurrent position of the device 104′ with respect to a desired positionfor the device 104′. For example, the indicator 1906 may emit a redlight to indicate that the device 104′ is outside of the travel rangesof the three ball screws (216 a, 216 b, 1804). In other words, a redlight is emitted when the working portion 204′ and pin 206′ can nolonger be articulated to reach a desired position, orientation, or adesired depth to insert the pin 206′. The indicator 1906 may emit ayellow light when the user is approaching the travel ranges and a greenlight when the pin 206′ is aligned with a virtual pin plane. Theindicator 1906 may further produce a blinking light that changes inblinking frequency based on how close the device 104′ is to exceedingthe travel range, or how close the pin 206′ is to a virtual pin plane.The indicator 1906 may also indicate when the device 104′ is ready toautonomously place the pin inside the bone. In a particular embodiment,the working portion 204′ does not actuate until the indicator 1906 is inan active state, where the active state is triggered when the device104′ is within the travel limits of the ball screw. This data conveyedby the indicator 1906 is readily available based on either: a) localdata collected directly from the device 104′, such as the devicekinematics; b) the tracking data collected from the tracking system 106;c) a comparison of the POSE of the device 104′ with the surgical plan;or d) a combination thereof.

In a specific embodiment, with reference to FIGS. 20A and 20B, thearticulating device 104′ includes a partial enclosure 2002. FIG. 20A isperspective view of the articulating device 104′ with the partialenclosure 2002 and FIG. 6B is a cross-section view thereof. The partialenclosure 2002 is attached to the hand-held portion 202 and partiallyencloses the working portion 204′. The working portion 204′ is able toarticulate within the partial enclosure 2002. The partial enclosure 2002has an internal dimension (i.e. height or diameter) of ‘h’ thatcorresponds to the travel range of the working portion 204′. Thisdimension ‘h’ may account for the translation ‘d’ of the working portion204′ and any additional height required to account for the pitch ‘a’ ofthe working portion 204′. The advantage of the partial enclosure 2002 isto provide the user with a guide as to the workspace or travel range ofthe working portion 204′. The user can simply place a front end of thepartial enclosure 2002 on the bone to stabilize the hand-held portion202, at which time the working portion 204′ can articulate to a virtualpin plane and drive the pin 206′ into the bone. The user is no longertrying to aim the small pin 206′ directly to a pin plane, but is ratherusing a larger guide, the partial enclosure 2002, to get the pin 206′ inthe general vicinity of a pin plane and allowing the working portion204′ to perform the alignment. In addition, the user no longer has toworry about exceeding the travel limits of the working portion 204′while aligning the pin 206′.

The front end of the partial enclosure 2002 may act as a bone contactingelement (1904 a, 1904 b) to stabilize the hand-held portion 202 and mayfurther include features such as a jagged edge or one or more pointedprotrusions.

The pin 206′ extends beyond the partial enclosure 2002 in the extendedstate to allow the pin to be driven into the bone as shown in FIG. 6B.When the pin 206′ is in the retracted state, the pin 206′ is enclosedwithin the partial enclosure 2002.

The partial enclosure 2002 may further include the indicator 1906 to aidthe user in positioning the device 104′ to a desired pin plane asdescribed above.

The partial enclosure 2002 is further configured to allow the trackingarray 212 to attach with the working portion 204′, or an outer guard1802′ of the working portion 204′, to permit the tracking system 106 totrack the POSE of the working portion 204′ as it articulates.

In a particular embodiment, with reference to FIGS. 21A and 21B, thearticulating device 104′ includes a full enclosure 2102. FIG. 7A is aperspective view of the articulating device 102 with the full enclosure2102 and FIG. 7B is a cross-section view thereof. The full enclosure2102 is configured with the same principles and has the same advantagesas the partial enclosure 2002, except the tracking array 212 is attacheddirectly to the full enclosure 2102. Since the tracking array 212 isattached to the full enclosure 2102, the control scheme for controllingthe working portion 204′ must be modified, where the device kinematicsare used to determine the POSE of the working portion 204′.Particularly, the tracking system 106 tracks the hand-held portion 202based on the geometric relationship between the array 212 and thehand-held portion 202, and the actuator (210 a, 210 b) positions (i.e.the rotational position of the actuators that corresponds to theposition of the ball nuts (218 a, 218 b) on the ball screws (216 a, 216b)) are used to determine the POSE of the working portion 204′ withrespect to the hand-held portion 202. Therefore, the computing system102 can determine new actuator positions to control and align the pin206′ with a virtual pin plane.

It should be appreciated that the partial enclosure 2002 and fullenclosure 2102 may be sized and adapted for assembly to a hand-heldsystem having greater than two degrees of freedom with similaradvantages. For example, it is contemplated that the inner dimensions ofthe enclosure (226, 228) may accommodate the travel limits of a devicehaving an articulating portion that articulates in one or moretranslational directions, pitch, and yaw such as the system described inU.S. Pat. App. No. 20130060278. However, as the number of degrees offreedom increase, so does the size of the enclosure (226, 228) which mayimpede the operating workspace.

It should be further appreciated that the embodiments of the bonestabilizing member 1902, the indicator 1906, the partial enclosure 2002,and full enclosure 2102, can all be adapted for use with the 2-DOFsurgical device 104 as shown in FIGS. 2A-2B.

Bi-Cortical Drilling

To further stabilize the bone pins in the bone it may be desirable todrill the pins through two cortical regions of the bone, also referredto as bi-cortical drilling. However, if a drill bit or a pin is drilledbeyond the second cortical region and into the soft tissue, patient harmcan occur. Therefore, it is proposed that the third pin-drivingactuation axis can also be used to retract the drill bit/pin if thedrill bit/pin breaks through the second cortical region.

In a particular embodiment, bone breakthrough is detected using anexisting method, such as the method described in Taha, Zahari, A. Salah,and J. Lee. “Bone breakthrough detection for orthopedic robot-assistedsurgery.” APIEMS 2008 Proceedings of the 9th Asia Pacific IndustrialEngineering and Management Systems Conference. 2008, which is herebyincorporated by reference in its entirety. The articulating pin-drivingdevice 104′ then automatically retracts the drill bit/pin at a constantoptimal retraction speed relative to the bone, regardless of how theuser is moving the hand-held portion 202. This ensures that if the drillbit/pin breakthrough the second cortical region, that the drill bit/pinis retracted so as to not cause any patient harm. The retraction speedis a function of the optimal retraction speed combined with the currentspeed of the hand-held portion 202.

The relative speed between the hand-held portion 202 and the bone can bemeasured several different ways. In one embodiment, the speed of thehand-held portion 202 relative to the bone is not detected and instead aspeed is assumed. In another embodiment, a simple linear distancemeasuring tool is used, such as a laser distance measurement device. Ina particular embodiment, the tracking system 106 is used to track boththe bone and the hand-held portion 202 using one or more fiducialmarkers on each of the bone and the hand-held portion 202.

OTHER EMBODIMENTS

While at least one exemplary embodiment has been presented in theforegoing detailed description, it should be appreciated that a vastnumber of variations exist. It should also be appreciated that theexemplary embodiment or exemplary embodiments are only examples, and arenot intended to limit the scope, applicability, or configuration of thedescribed embodiments in any way. Rather, the foregoing detaileddescription will provide those skilled in the art with a convenientroadmap for implementing the exemplary embodiment or exemplaryembodiments. It should be understood that various changes can be made inthe function and arrangements of elements without departing from thescope as set forth in the appended claims and the legal equivalentsthereof.

The foregoing description is illustrative of particular embodiments ofthe invention, but is not meant to be a limitation upon the practicethereof. The following claims, including all equivalents thereof, areintended to define the scope of the invention.

1. A surgical device, comprising: a hand-held portion; a working portion movably coupled to the hand-held portion for driving a tool; a plurality of actuators for moving the working portion with respect to the hand-held portion, wherein each of the plurality of actuators has a travel range; and an indicator for indicating when at least one of the plurality of actuators is: (i) within the travel range; (ii) approaching a travel limit of the travel range; or (iii) outside the travel range.
 2. The surgical device of claim 1 wherein the each of the plurality of actuators are linear actuators comprising a motor for bi-directionally rotating a screw coupled with a nut.
 3. The surgical device of claim 1 wherein the indicator is a light.
 4. The surgical device of claim 5 wherein the light changes a first color for situation (i), a second color for situation (ii), and a third color for situation (iii).
 5. The surgical device of claim 1 further comprising a plurality of indicators.
 6. The surgical device of claim 1 wherein the tool is a saw blade and the working portion is configured to oscillate the saw blade.
 7. The surgical device of claim 6 further comprising the saw blade.
 8. The surgical device of claim 1 wherein the indicator is coupled to the hand-held portion or the working portion.
 9. The surgical device of claim 8 wherein the indicator is coupled to the working portion.
 10. The surgical device of claim 1 wherein the plurality of actuators move the working portion with respect to the hand-held portion in response to control signals to maintain alignment of an axis of the tool with a plane having a pre-determined location relative to a bone.
 11. The surgical device of claim 10 further comprising a computer configured to receive inputs comprising the pre-determined location of the plane and a location of at least one of the bone and the surgical device, wherein the computer comprises a processor configured to generate the control signals and activate the indicator using the inputs.
 12. The surgical device of claim 11 wherein the input corresponding to the location of the surgical device is an input corresponding to a position and orientation (POSE) of three or more fiducial markers coupled to the working portion, wherein the POSE of the three or more fiducial markers is determined by a tracking system.
 13. The surgical device of claim 10 wherein the pre-determined location of the plane is a pre-determined location for a cut surface to be created on the bone.
 14. The surgical device of claim 13 wherein the bone is subject to knee arthroplasty.
 15. The surgical device of claim 1 wherein the indicator indicates when all or a subset of the plurality of actuators is: (i) within the travel range; (ii) approaching a travel limit of the travel range; or (iii) outside the travel range.
 16. A surgical system, comprising: a surgical device, comprising: a hand-held portion; a working portion movably connected to the hand-held portion for driving a tool; a plurality of actuators for moving the working portion with respect to the hand-held portion, wherein each of the plurality of actuators has a travel range; and an indicator for indicating when at least one of the plurality of actuators is: (i) within the travel range; (ii) approaching a travel limit of the travel range; or (iii) outside the travel range; and a computing system comprising one or more processors configured to activate the indicator.
 17. The surgical system of claim 16 wherein the each of the plurality of actuators are linear actuators comprising a motor for bi-directionally rotating a screw coupled with a nut.
 18. The surgical system of claim 16 wherein the indicator is a light.
 19. The surgical system of claim 16 wherein the light changes a first color for situation (i), a second color for situation (ii), and a third color for situation (iii).
 20. The surgical system of claim 16 further comprising a plurality of indicators.
 21. The surgical system of claim 16 wherein the tool is a saw blade and the working portion oscillates the saw blade.
 22. The surgical system of claim 21 further comprising the saw blade.
 23. The surgical system of claim 16 wherein the indicator is coupled to the hand-held portion or the working portion.
 24. The surgical system of claim 16 wherein the indicator is coupled to the working portion.
 25. The surgical system of claim of 16 wherein the plurality of actuators move the working portion with respect to the hand-held portion in response to control signals.
 26. The surgical system of claim 25 wherein the computing system is configured to receive inputs comprising a pre-determined location of a plane relative to the bone and a location of at least one of the bone and the surgical device, wherein the computing system comprises one or more processors configured to: (a) generate the control signals, using the inputs, to maintain alignment of an axis of the tool with the plane; and (b) activate the indicator.
 27. The surgical system of claim 26 wherein the input corresponding to the location of the surgical device is an input corresponding to a position and orientation (POSE) of three or more fiducial markers coupled to the working portion, wherein the POSE of the three or more fiducial markers is determined by a tracking system.
 28. The surgical system of claim 27 further comprising the tracking system.
 29. The surgical system of claim 26 wherein the pre-determined location of the plane is a pre-determined location for a cut surface to be created on the bone.
 30. The surgical system of claim 16 wherein the bone is subject to knee arthroplasty.
 31. The surgical system of claim 16 wherein the computing system comprises one or more computers and at least one of the computers is housed in the surgical device. 